Manual follow-up
A personal message or call is warm and direct, and when you remember to send it, it works. There is nothing wrong with the approach itself.
It depends entirely on your memory and your time. When the week gets busy, follow-up is the first thing to slip, and the records you forget are the ones that quietly go unpaid.
RemKliQ runs the follow-up for you on schedule, so nothing depends on remembering and nothing slips on a busy week.